Restricting AD replication traffic and client RPC traffic to a specific port: http://support.microsoft.com/kb/224196/

How to configure RPC dynamic port allocation to work with firewalls: http://support.microsoft.com/kb/154596/en-us

The default dynamic port range for tcp/ip has changed in Windows vista and Windows 2008: http://support.microsoft.com/kb/929851

Service overview and network port requirements for Windows server system: http://support.microsoft.com/kb/832017/